Explosive composition



Patented Nov. 14, 1944 UNITED STATES EXPLOSIVE COMPOSITION Clyde OliverDavis, Woodbury, and Hartwell Henry Fassnacht, Wenonah, N. 1., assignorsto E. I. du Pont de Nemours & Company, Wilmington, Del., a corporationof Delaware No Drawing. Application April 1, 194 2, Serial No. 437,228

4 Claims.

This invention relates to a high explosive composition, and moreparticularly to a modified blasting gelatin.

Blasting gelatin is one of the strongest commercial explosives, beingconsidered to have essentially 100% of the strength of nitroglycerin. Itcomprises over 90% of nitroglycerin ordinarily, and between 4 and 8% ofdissolved nitrocotton, whereby it takes on a tough, rubbery consistency.It is customary to include in the composition, also, around 1.0% of anacid accepting material such as calcium carbonate. A portion of thenitrocotton may likewise be replaced by other ingredients.

One of the principal uses of blasting gelatin is in the shooting of oilwells, where it is lowered to great depths in the well, for example, to5,000 or 10,000 it. or more. Under the high pressures encountered atsuch depths, it is essential that the blasting gelatin remainsufficiently sensitive to propagate the explosion throughout the entiremass. It is important, also, that the velocity of detonation be at themaximum, and not of a low order, if satisfactory execution is to beobtained. Some difflculties with respect to sensitiveness and velocityhave been encountered in the case of explosives of this type as madeheretofore.

An object of the present invention is a gelatinized explosive high innitroglycerin and possessing very favorable properties under conditionsof confinement by high pressures. A further object is a modifiedblasting gelatin characterized by an improved degree of sensitiveness topropagation. A further object is such an explosive capable of detonationat its maximum velocity under unfavorable conditions. A still furtherobject is a modified blasting gelatin containing an added ingredientwhich imparts superior properties thereto. Additional objects will bedisclosed as the invention is describedmore at lengthhereinafter.

We have found that the foregoing advantages are attained when weintroduce into a blasting gelatin composition a relatively small amountof an oxide of a metal of a certain .group. We find that the oxideswhich bring about this favorable effect are those taken from the classof metals consisting of manganese, copper, titanium, lead, tin, andiron, particularly ferric iron. In the manufacture of blasting gelatin,the customary procedure is to introduce the requisite amount of liquidnitroglycerin into the mixing bowl at the proper temperature. Theweighed amounts nitrocotton and other ingredients are then added,together with the inorganic oxide. Agitation is then started and mixingcontinued until thorough incorporation and gelatinization have resulted.

The following examples will serve to illustrate more clearly the methodof carrying out our invention and the advantages resulting therefrom.

Example 1 Blasting gelatins in 1%" diameter cartridges were preparedhaving nitroglycerin contents of 91% and suitable proportions ofnitrocotton, together with small quantities of an inorganic ox- 10 ide.Tests were carried out on standard blasting gelatin and on similarexplosives containing oxides of tin, manganese, and lead, respectively.The following results were obtained:

1 iensgltiveness a 0 Fishing Velocity after Oxide Amount g gfg gg 2months storage storage at 120 F.

Per cent Inches one 0 Failed to shoot.

1 1 6,560 m./sec.

1 12 7,140 mJsec.

1 2 6,670 m./sec.

In the foregoing tabulation, the sensitiveness results were obtained byseparating two sticks of the blasting gelatin by definitely spacedintervals and determining the greatest distance at which consistentdetonations of the second cartridge were obtained as the result of thedetonation of the first cartridge and propagation of the resultingexplosive wave across the air gap. From the above tabulation it is seenthat, in the case of the standard blasting gelatin, the explosive didnot propagate even when there was no air gap,

while in the presence of 1% MnOz propagation took place across a gap of12". With the blasting gelatins containing tin and lead oxides,intermediate increases in sensitiveness were obtained as well as animprovement in velocity. While the standard failed to shoot in thevelocity test, the samples containing the various oxides detonated athigh velocity, the blasting gelatin containing manganese dioxide showingthe high velocity of 7140 meters per second.

Example 2 Similar mixings of blasting gelatins were tested in the samemanner, with the following results:

Oxide Amount sensitiveness Inches The advantages of the presence ofcopper oxide, ferric oxide, and titanium dioxide are shown by theincreased sensitiveness obtained.

Example 3 Sensitiveness Velocity Oxide Amount 7 1 th 1 th man man may at120 F. at 120 F.

Percent Inches Inches None 22 7, 290 Failed.

(Failed) ItInOg "I l 15 10 6, 860 7, 651).

The foregoing examplesshow strikingly the improvement in blastinggelatins by the inclusion of small amounts of certain finely dividedmetal oxides, especially with regard to the retention of their initialproperties after storage under severe conditions. We find an amountbetween 0.1 and 5.0% of the oxide to be desirable, and our preferredrange is between 0.4 and 2%. While various inorganic oxides haveimproved the properties of the blasting gelatins, we find manganesedioxide to be particularly effectivein this respect.

It is essential for the attainment of the several advantages of theinvention that'the inorganic oxide be in finely "divided form.Preferably, such oxide will be sufficiently fine that substantially allwill pass a IOU-mesh screen. In the case of manganese dioxide, ourpreferred material, advantageous results have been obtained when usingmaterial such that the greater part passed a 30-mesh screen but was heldon a 65-mesh screen. The use of 100+ material, however, gives morecertain results.

Our invention has been described as particularly applicable to blastinggelatins. While this is the place of maximum advantage, we find theoxides mentioned to give improvement in the case of blasting gelatins,thenitroglycerin content will ordinarily be above 90%. When the termnitroglycerin is used, we intend this to include not only the chemicalcompound itself but also nitroglycerin containing other dissolvednitrated materials, such as ethylene glycol dinitrate, nitrated sugars,nitrated polymerized glycerin, dinitrochlorhydrin, and the like, whichcase of all gelatinizedexplosives containing more than nitroglycerin orother liquid explosive nitric ester. Desirably such explosives will havea nitroglycerin content of over 88%, and, in the have been added 'forthe purpose of depressing the freezing point, or for other reasons.While the examples and description have disclosed nitrocotton as thegelatinizing agent for the nitroglycerin, itwillflbe understood thatother appropriate forms of nitrocellulose may be used. We likewise findthe invention best adapted to gelatinized' compositions containing arelatively high ratio of nitrocellulose to liquid explosive nitricester, for example not less than 1 part of the former to 25' parts ofthe latter; In other words, the invention is especially adapted totough, rubbery compositions such as blasting gelatins and to gelignitetypes, but not limited thereto.

We have described our invention at length in the foregoing. It will beunderstood, however, that many variations may be introduced withoutdeparture from the scope of the invention. We intend to be limitedtherefore only by the following patent claims:

1. A high explosive composition comprising more than 80% of a, liquidexplosive nitric ester, nitrocellulose, and between 0.1% and 5.0% of aninorganic oxide in finely divided form taken from the group consistingof the oxides of manganese, copper, titanium, lead, tin, and ferriciron.

2. A modified blasting gelatin containing more, than 88% of a liquidexplosive nitric ester, nitrocellulose, and between 0.1 and 5.0% of afinelydivided inorganic oxide taken from the group consisting of theoxides of manganese, copper, titanium, lead, tin, and ferric iron.

3. A modified blasting gelatin comprising at least 90% of nitroglycerin,nitrocellulose as gelatinizing agent, and between 0.1 and 5.0% ofmanganese dioxide.

4. A modified blasting gelatin containing more than 88% of a liquidexplosive nitric ester, nitrocellulose, and between 0.1 and 5.0% of aninorganic oxide of such degree of fineness that substantially thegreater part will pass a IOO-mesh screen, said oxide being takenfrom thegroup consisting of the oxides of manganese, copper, titanium, lead,tin, and ferric iron.

CLYDE OLIVER DAVIS. HARTWELL HENRY FASSNACHT.

